:root {
    --background-color: #2c3e50;
    --border-color: #7591AD;
    --text-color: #34495e;
    --color1: #EC3E27;
    --color2: #fd79a8;
    --color3: #0984e3;
    --color4: #00b894;
    --color5: #fdcb6e;
    --color6: #e056fd;
    --color7: #F97F51;
    --color8: #BDC581;
}

* {
    margin: 0;
    padding: 0;
}

html {
    font-size: 14px;
}

body {
    width: 100vw;
    height: 100vh;
    background-color: var(--color5);
    font-family: 'Montserrat', sans-serif, Arial, 'Microsoft Yahei';
}

.container {
    position: relative;
    width: 100vw;
    height: 100vh;
    /* 防止出现滚动条 */
    overflow: hidden;
}

.bubble {
    position: absolute;
    width: 40px;
    height: 40px;
    background-color: #fff;
    bottom: 0;
    opacity: .6;
    border-radius: 100%;
    animation: flying 3s ease-in-out infinite;
}

.bubble:nth-child(3n+1) {
    left: calc(90px * var(--i));
    width: calc(3px * var(--i));
    height: calc(3px * var(--i));
    animation-duration: calc(0.3s * var(--i));
}

.bubble:nth-child(3n+2) {
    left: calc(50px * var(--i));
    width: calc(4px * var(--i));
    height: calc(4px * var(--i));
    animation-duration: calc(0.5s * var(--i));
}

.bubble:nth-child(3n+3) {
    left: calc(20px * var(--i));
    width: calc(2px * var(--i));
    height: calc(2px * var(--i));
    animation-duration: calc(0.4s * var(--i));
}

@keyframes flying {
    0% {
        /* 移除可是范围 */
        bottom: -50px;
        transform: translateX(0px);
    }
    25% {
        transform: translateX(20px);
    }
    50% {
        transform: translateX(100px);
    }
    75% {
        transform: translateX(130px);
    }
    100% {
        bottom: 900px;
        transform: translateX(-10px);
    }
}